Device for outputting single sheets from a printer

ABSTRACT

A method and device for output of single sheets from a printer employs a driven first roller pair having a conveying nip in which a respective single sheet is transported and deflected from an approximately vertically proceeding conveying path into an approximately horizontal conveying path. A separation element that suppresses a continued conveying of the respective single sheet on a circumferential surface of a lower roller of the roller pair is arranged in a proximity of the circumferential surface of the lower roller. An edge sensor is arranged preceding the roller as viewed in a conveying direction for determining whether single sheets have pushed on top of one another. A discharge brush electrically discharges one side of the single sheet arranged in the conveying path following the roller pair. A deflection device deflects the single sheet emerging from the conveying nip into a substantially horizontal attitude shortly before the conveying nip as viewed in a direction of the conveying path. The discharge brush is mounted to the end of the deflection device.

BACKGROUND OF THE INVENTION

The invention is directed to a device for outputting single sheets froma printer or a copier, comprising a driven roller pair in whoseconveying nip the respective single sheet is transported and which isdeflected from an approximately vertically proceeding conveying pathinto an approximately horizontal conveying path, and comprising adeposit compartment for the deposit of the conveyed single sheets.

Such a device is utilized, for example, in high-performance printers,whereby the deposit compartment is a specimen compartment in which, forexample, individual sheet specimens of a test printing are deposited.Traditional apparatus have shown that their operating dependability islimited and a paper jam in the output region occurs disproportionatelyoften.

JP-A-57 072561 discloses a device for outputting single sheets from aprinter or copier. The single sheets are conveyed forward by a rollerpair. A rejector unit that suppresses a further-conveying of therespective single sheet on the circumferential surface of this roller isarranged at the roller.

U.S. Pat. No. 4,511,238 discloses a device in an electrophotographicallyworking copier. This device successively supplies single sheets tofurther units. A sensor, for example a mechanical sensor, acquires thepresence of a single sheet between conveyor rollers.

U.S. Pat. No. 4,570,801 discloses a device for conveying single sheets.An optoelectronic sensor checks the conveyed single sheets. When a jamoccurs, for example due to single sheets sliding on top of one another,this jam is reported to a higher-ranking control.

JP-A-58 089557 discloses a paper output unit of a copier machine wheresingle sheets are conducted between rollers. Each single sheet passes aguide that assures that the single sheet is supplied to a depositcompartment.

SUMMARY OF THE INVENTION

An object of the invention is to specify a device for the output ofsingle sheets that works operationally dependably and avoids a paperjam.

This object is achieved by the initially cited device in that arejection unit is arranged in the proximity of the circumferentialsurface of the lower roller of the roller pair, this rejection unitsuppressing a continued conveying of the respective single sheet on thecircumferential surface of the lower roller.

The invention is based on a perception that it is precisely the lowerroller of the roller pair that is critical, since single sheets arestill held at the generated surface due to electrostatic forces or theforce of gravity in the transition between vertical conveying andhorizontal conveying, and can be drawn into the structural necessary gapbetween lower roller and deposit compartment, whereby they can cause apaper jam. According to the invention a rejection or separating elementis arranged in the proximity of the circumferential surface of the lowerroller. This rejection or separating element lifts the respective singlesheet off from the generated surface of the lower roller, and adhesionof the single sheet is no longer possible. The single sheet is compelledto pass through the discharge gap between roller pair and depositcompartment. The present invention thus works operationally dependablyand reliably.

The generated surface of the lower roller preferably has at least onechannel-shaped recess into which the rejection or separating elementengages. When this rejection unit is designed as a flashing, it hasfront, finger-like sections engaging into the recess or into a pluralityof recesses on the generated surface of the lower roller. As a result ofthis arrangement, the single sheet is reliably lifted off from thegenerated surface of the lower roller, as a result whereof a wrapping ofthe lower roller is made impossible.

According to the invention, a discharge brush which preferablyelectrically discharges that side of the single sheet lying up isarranged in the conveying path following the roller pair. The dischargebrush is thus arranged at a position such that the single sheet is nolonger in frictional contact with conveyor elements. The electrostaticdischarge of the sheet can thus no longer be reversed by such conveyorelements. The single sheets deposited in the deposit compartment thus donot adhere due to electrostatic effects and can be easily individuallyseparated from one another.

In the invention, an edge sensor with the assistance of which adetermination can be made as to whether prescribed intervals are adheredto between single sheets following one another is arranged preceding theroller pair as viewed in a conveying direction. The structure of such anedge sensor is known in and of itself For example, the edge sensor canbe designed as a light barrier that indicates the lack of a sheet withinthe light barrier. When conveyed single sheets slide on top of oneanother in the conveying path, then the edge sensor can no longer detecta starting edge or, respectively, ending edge of single sheets. Such acondition is then interpreted as a paper jam. The operatingdependability of the apparatus is further enhanced by this technique.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the output-side apparatus according to theinvention for a high-performance printer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An exemplary embodiment of the invention is described below withreference to the single Figure. This Figure shows the output-sideapparatus section of a high-performance printer that successively printssingle sheets. The single sheets 12 are individually successivelydeposited in a specimen or sample compartment and can be removedindividually or as a packet. A roller pair 18 with an upper roller 20and a lower roller 22 serves the purpose of forward conveying of thesingle sheets 12. The single sheets 12 are conveyed up via a verticallyproceeding paper channel 24, reach the conveying nip in the roller pair18, are subsequently diverted into a horizontal attitude and are thendeposited in the specimen or sample compartment 14.

The lower roller 22 has annular recesses in the fashion of channels onits generated surface. Fingers of a flashing or baffle 26 as aseparation element engage into these channels. When conveying singlesheets 12 through the conveying nip, the flashing 26 reliably lifts orseparates the respective single sheet 12 from the generated surface ofthe lower roller 22, so that it cannot remain adhering to the surface ofthe lower roller 22 due to the force of gravity or due to electrostaticforces.

The single sheets conveyed through the conveying nip are redirected by adeflection element 28, i.e. the conveyed edge of a conveyed single sheetstrikes the arced, leading surface 30 inclined in the direction of thehorizontal line in the deflection unit designed as a profile, wherebythe single sheet 12 is deflected little by little from the verticalpaper channel 24 via the conveying nip and the deflection element ordevice 28 into a horizontal attitude and is then gently output onto thestack of single sheets 12 in the specimen compartment 14.

The attack angle of the surface 30, the angle of the plane proceedingthrough the rotational axes 32, 34 of the roller pair 18 and thebent-over end 36 of the guide profile arranged in the paper channel 24are matched to one another such that the respective single sheet 12 isdeflected from the vertical into the horizontal upon exertion of slightforces.

At its end remote from the roller pair 18, the deflection element ordevice 28 carries a discharge brush 40 that frees the upper side of thesingle sheet 12 from electrostatic charges. Since this upper side of thesingle sheet 12 subsequently no longer comes into contact with furtherconveyor elements, a renewed electrostatic charging cannot occur. Thesingle sheets 12 of the stack 10 can thus be also easily withdrawnindividually without overcoming electrostatic forces.

A light barrier 42 is arranged preceding the roller pair 18 as viewed inthe conveying direction. Whether prescribed intervals are still presentbetween successive single sheets 12 or whether single sheets haveslipped on top of one another as a result of a paper jam can berecognized with the assistance of this light barrier. When the latter istrue, then a control signal that indicates a paper jam condition andpotentially shuts down the printer can be determined from the signal ofthe light barrier.

A further roller pair 44 is shown in FIG. 1 that supplies single sheetsto a further output compartment (not shown). Dependent on the positionof the shunt 46, single sheets are supplied either to the roller pair 18(this condition is shown in the Figure) or to the roller pair 44.

The apparatus of the invention makes it possible to arrange thedischarge opening behind the roller pair 18 relatively far toward thetop at the upper end of the entire frame 48 of the printer, as a resultwhereof the stacking capacity of the specimen or sample compartment 14is enlarged. The combination of baffle or flashing 26, deflectionelement or device 28 and discharge brush 40 means that a paper jam isavoided and the overall output of single sheets into the specimencompartment 14 occurs reliably. Although various minor changes andmodifications might be proposed by those skilled in the art, it will beunderstood that our wish is to include within the claims of the patentwarranted hereon all such changes and modifications as reasonably comewithin our contribution to the art.

What is claimed is:
 1. A device for output of single sheets from aprinter or copier, comprising: a driven roller pair having a conveyingnip in which a respective single sheet is transported and is deflectedfrom an approximately vertically proceeding conveying path into anapproximately horizontal conveying path; a deposit compartment fordepositing the conveyed single sheets; a separation element thatsuppresses a continued conveying of the respective single sheet on acircumferential surface of a lower roller of said roller pair, saidseparation element being arranged in a proximity of the circumferentialsurface of the lower roller; an edge sensor arranged preceding theroller pair as viewed in a conveying direction, said edge sensordetermining whether single sheets have pushed on top of one another as aresult of a paper jam; a discharge brush which electrically dischargesone side of the single sheet arranged in the conveying path followingthe roller pair; a deflection device that deflects the single sheetemeroing from said conveying nip into a substantially horizontalattitude; and said discharge brush being mounted to said deflectiondevice.
 2. The device according to claim 1 wherein the lower roller hasat least one channel-shaped recess at a generated surface of the lowerroller into which the separation element engages.
 3. The deviceaccording to claim 2 wherein the separation element is designed as abaffle that has front, finger-like sections engaging into one or more ofsaid channel-shaped recesses on said generated surface of the lowerroller.
 4. The device according to claim 1 wherein the deflection deviceis designed as a deflection profile which accepts said discharge brushat an end remote from the roller pair.
 5. The device according to claim1 wherein a plane proceeding through rotational axes of the roller pairdescribes an angle of 30-60° with vertical.
 6. The device according toclaim 1 wherein the separation element is arranged between the lowerroller and the deposit compartment such that a single sheet is liftedoff from a generated surface of the lower roller and is conducted tosaid deposit compartment.
 7. The device according to claim 1 wherein thedeposit compartment is an externally freely accessible outputcompartment of a high performance printer having a plurality of outputcompartments.
 8. A device for output of single sheets from a printer orcopier, comprising: a driven roller pair having a conveying nip in whicha respective single sheet is transported and is deflected from anapproximately vertically proceeding conveying path into an approximatelyhorizontal conveying path; a deposit compartment for receiving thesingle sheets conveyed from said nip; a separation element thatseparates the respective single sheet from a circumferential surface ofa lower roller of said roller pair; an edge sensor arranged precedingthe roller pair as viewed in a conveying direction, said edge sensordetermining whether single sheets have pushed on top of one another as aresult of a paper jam; a discharge brush which electrically dischargesone side of the single sheet and which is arranged in the conveying pathfollowing the roller pair; a deflection device having a deflectionsurface that deflects the single sheet emerging from said conveying nipinto a substantially horizontal attitude; and said discharge brush beingpositioned at the deflection surface.
 9. A method for output of singlesheets from a printer or copier, comprising the steps of: providing, adriven roller pair having, a conveying nip in which a respective singlesheet is transported to a deposit compartment for depositing of theconveyed single sheets; conveying the single sheets from the printer orcopier vertically upwardly towards the roller pair nip; prior to entryof the single sheets into the roller pair nip utilizing an edge sensorto determine whether single sheets have pushed on top of one another;providing a separation element for separating the respective singlesheet from a circumferential surface of a lower roller of the rollerpair; engaging a leading end of the sheets in the roller pair nip andthen outputting the sheets so that they strike a deflection element asthey are separated away from the lower roller by the separation element,the deflection element having a deflection surface deflecting the sheetsdownwardly, and conveying the sheets into contact with and past adischarge brush positioned at the deflection surface to electricallydischarge one side of the single sheet; and depositing the sheets in thedeposit compartment.
 10. The method according to claim 9 including thestep of lifting the sheets with the separation element by having fingersof the separation element engage underneath the sheets where fingers ofthe separation element engage in grooves of the lower roller.